Just posting this for reference in case anyone's curious. I couldn't find this info elsewhere so maybe it'll answer questions for someone in the future.
Our host has some good info on which trannies were used in which years and pictures showing whether they are forward- or top-shift here:
https://www.marlincrawler.com/transmissionFor older trucks with the G52, G54, and G58 transmissions, the W56-C, D, and E are the best option for a W56 series swap as they are forward-shift whereas the W56-A, and -B are top-shift and would require significant cutting of the floor and probably removal of the console (if your truck has one) to get the transfer case shifter in.
The W56-C (and I assume the D and E are the same but that's just my assumption) gear shifter is in roughly the same place as the G series but the transfer case shifter is about 1" further back. I think this will be okay on my '84 truck as the hole in the floor and the openings in the console appear to have plenty of room for this though it's going to look a little odd.
the transfer case on both transmissions is externally identical and their overall length is the same so measuring from the top-shift block-off plate is a good point of reference.
Here is the G52 shifters measured to the block-off plate:
DSC_1343 by
Will Baker, on Flickr
Here is the W56-C shifters measured to the block-off plate:
DSC_1342 by
Will Baker, on Flickr